This project will utilize sensitive, early biomarkers of disease risk, including whole body adiposity with DEXA, HTGC and CIMT, directly relevant to diabetes and cardiovascular disease risk. The primary goals of this study are to deliver an evidence-based weight loss intervention to the population of youth who are overweight or obese as a result of antipsychotic treatment, to characterize metabolic risk associated with weight using sensitive biomarkers, and to evaluate the magnitude of change observed in these biomarkers in children receiving an established behavioral weight-loss intervention. This study will completed in two phases.